British prime minister Theresa May will on Monday say 95 per cent of Britain’s Brexit deal has been agreed but repeat her opposition to a European Union proposal for the Irish Border, a major stumbling block, as criticism within her party grows.

Facing some of the fiercest attacks to date over her Brexit plans after again failing to clinch a deal at an EU summit last week, Mrs May will try to calm passions in parliament where her strategy has angered eurosceptics and EU supporters alike.

With just over five months until Britain is scheduled to exit the EU, talks have stalled over a disagreement on the so-called Northern Irish “backstop”, an insurance policy to ensure there will be no return to a hard border on the island of Ireland if a future trading relationship is not agreed in time.

But Mrs May’s attempt to unlock the talks by considering an extension to a status-quo transition period beyond the current proposed end date of December 2020 has further riled both pro- and anti-EU factions in her deeply split Conservative Party.

In an attempt to highlight how much progress has been made in more than a year of talks with the EU, she will tell parliament the government has reached agreement on everything from Gibraltar to future security over the last three weeks.

Some of an estimated 700,000 strong protest during the People’s Vote March on Saturday, which called for a vote on the final Brexit deal. Photograph: EPA

Withdrawal Agreement

“Taking all of this together, 95 per cent of the Withdrawal Agreement and its protocols are now settled,” Mrs May will say, according to excerpts from her statement to parliament.

“The shape of the deal across the vast majority of the Withdrawal Agreement is now clear.”

But the deal - the terms of Britain’s divorce - cannot be signed off until the two sides settle on future management of the border between Northern Ireland, a British province, and EU member state Ireland.

Both sides are committed to keeping the Irish Border open, a key aspect of a 1998 peace deal that ended decades of Irish sectarian bloodshed.

The EU proposal - for Northern Ireland to remain in the bloc’s customs union - has been rejected by Mrs May as it would potentially create barriers to trade with the rest of Britain, something ruled out by a pro-Brexit Northern Irish party that props up her minority government.

At an EU summit in Brussels last week, any agreement seemed just as far off as it did months earlier, with EU officials and diplomats saying Mrs May had offered nothing new to ease the deadlock.

Since then, her proposal to extend the transition period has stoked anger among Conservative eurosceptics, who fear she is leading Britain into a deal that will make Britain “vassal state” indefinitely - unable ever to fully leave the EU.

Critics of Mrs May used Britain’s Sunday newspapers to rhetorically savage the British leader, with unnamed rivals using phrases such as “assassination is in the air”.

A vote of no-confidence in Mrs May would be triggered if 48 Conservative lawmakers submit letters to the chairman of the party’s so-called “1922 Committee” of backbenchers demanding such a vote.

The Sunday Times said 46 had now been sent.

Private meeting

The newspapers reported Mrs May had been summoned to address Conservative lawmakers in a private meeting on Wednesday. The Daily Telegraph said she had held a 90-minute conference call with her top ministers on Sunday to shore up support.

On Wednesday one prominent hardline Brexiteer, former junior Brexit minister Steve Baker, will try to block the EU’s backstop plan by attaching amendments to legislation passing through parliament that would effectively make the proposal illegal.

Mrs May used a piece in Monday’s Sun newspaper to stress the Brexit negotiations were not about her and her future.

“When I’m confronted with tough choices during the Brexit negotiations, I don’ think about what the implications are for me. Instead, I ask myself what it means for you, for your family and for the whole of the United Kingdom, ” she wrote.

“Because the Brexit talks are not about me or my personal fortunes. They’re about the national interest - and that means making the right choices, not the easy ones.”

On Sunday, The UK’s Brexit minister Dominic Raab pushed forward the suggestion of extending the transition period, saying London could accept such a move if the EU dropped its proposal for a backstop without time limit, which May says would tear Northern Ireland away from mainland Britain. - Reuters